A new diagnostic algorithm for early prediction of vascular compromise in 208 microsurgical flaps using tissue oxygen saturation measurements.

The purpose of the study was to evaluate the detection of vascular complications earlier than clinical evidence using a noninvasive near-infrared tissue oximeter monitor. Early detection of circulatory compromise allows for earlier re-exploration and better outcomes. The monitoring method studied was the ViOptix T.Ox Tissue Oximeter (ViOptix Inc., Fremont, CA). The device uses an optical tissue characterization based on measuring scattering and absorption of near infrared light. Tissue oxygen saturation and its derivates were evaluated as candidates for a more sensitive algorithm to predict vascular flap complications. Criteria studied in various combinations were the absolute value of tissue oxygen saturation (StO2), the amount of its change (DeltaStO2) and the rate of its change (DeltaStO2/Deltat). There were 208 monitored breast flaps in 145 patients (62 bilateral and 83 unilateral). In 1 patient, 2 flaps were used to make a single breast. Patients were monitored intraoperatively and postoperatively for 36 hours. No flap being monitored was lost. Among the 208 flaps monitored, 5 patients exhibited complications that were predicted by the tissue oximeter before clinical signs were evident. If blood flow was completely occluded by either venous or arterial thrombosis, the tissue oximeter provided information that enabled diagnosis to be made in about 1 hour. The drop rate indicator DeltaStO2/Deltat, when it is equal to or greater than 20% per hour sustained more than 30 minutes predicted vascular complications. The use of the new diagnostic algorithm with the T.Ox Tissue Oximeter monitor was successful in predicting flap complication within 1 hour of the onset of the occlusive event with a high diagnostic accuracy in the 208 flap procedures.